Pneumatic tire with reinforcing belt that minimizes belt end gyroscopic effect

ABSTRACT

The pneumatic tire incorporates a reinforcement belt comprising two superposed median plies of metallic material and two laterally disposed marginal plies of nonmetallic material. The marginal plies are folded to form superposed flaps, with the corresponding flaps of each marginal ply being substantially aligned. 
     In all embodiments of the invention at least one pair of corresponding opposite, laterally disposed flaps align with one of the median plies. In at least one embodiment of the invention the second pair of opposite, laterally disposed flaps align with the second median ply. In other embodiments of the invention the second pair of opposite, laterally disposed flaps overlap the terminal ends of the second median ply. And in still further embodiments of the invention the second pair of opposite, laterally disposed flaps are positioned radially outward or radially inward of the second median ply. In all embodiments of the invention there are at least two and at the most three layers of ply material at various points along the crosswise width of the reinforcing belt.

The present invention relates to pneumatic tires and more particularlyto a pneumatic tire having an improved reinforcement belt construction.

The invention is especially applicable to radial carcass pneumatictires. The term radial, as used herein, refers to directionsperpendicular to the axis of rotation of the tire, and the termcrosswise refers to directions parallel to said axis.

Tires having reinforcement belts are well known and generally includeone or more plies of rubberized fabric reinforced with parallelfilaments, cords or cables. A common type of reinforcement beltgenerally includes one or more plies incorporating metallic filaments orcables, associated with one or more plies incorporating nonmetallicfilaments or cables.

In one known tire construction the reinforcement belt comprises a firstpair of laterally spaced plies incorporating metallic cables. The pliesare folded and substantially aligned in a crosswise direction with thefolded portions forming one lateral crosswise extremity. A second pairof laterally spaced plies incorporating nonmetallic cables are alsofolded and substantially aligned, with the folded portion forminganother lateral crosswise extremity. The first pair of folded plies issuperposed with the second pair of folded plies, the folded ends of thesecond pair extending crosswise beyond the folded ends of the first pairwithout encompassing or bracketing the first pair.

One of the problems present in this known tire construction is anundesirable gyroscopic effect caused by the belt that adversely affectssteering of the tires. This gyroscopic effect, which is attributable inpart to a relatively large belt mass at the extreme lateral edges ormarginal regions of the reinforcement belt, is especially noticeableduring high speed movement of the tires. For example, any rotation ofthe steering wheel which changes the spin axis of the steered wheels isopposed by a gyroscopic restoring torque that is a function of theangular momentum of the steered wheels.

Another problem present in known tire constructions having reinforcingbelts is the tendency of the marginal folds of a ply incorporatingmetallic cable to separate from the tread. The likelihood of suchbreakage can be reduced by using cables having finer wires, strands orfilaments, but at considerably more cost than the coarser cablecomponents.

A further problem of known tires with reinforcing belts is a decrease intravelling comfort due to the presence of relatively rigid metallicconstituents at the edge portions of the reinforcing belt that can causethe tire to reflect or amplify unsmooth road conditions. This isespecially apparent with tires having a reinforcing belt that comprisesplies of metallic cables only. Such tires are relatively inadequate indeforming to permit expansion. Moreover the vulcanization and formationof profiles in the tread of such tires often requires complex andexpensive molds having multiple segments.

It is thus desirable to provide a pneumatic tire having a reinforcementbelt construction that minimizes the problems of gyroscopic effect andbelt end separation, yet furnishes improved travel comfort, and iseconomical to manufacture.

Among the several objects of the invention are the provision of apneumatic tire having a novel reinforcement belt construction ofrelatively low belt mass at the marginal edge portions of thereinforcing belt. A pneumatic tire incorporating a novel reinforcementbelt construction which minimizes the likelihood of separation betweenthe tread and the plies incorporating metallic cable, and a tire havinga reinforcing belt construction that affords improved travelling comfortand is relatively inexpensive to manufacture. Other objects and featureswill be in part apparent and in part pointed out hereinafter.

The present invention relates to a pneumatic tire wherein an annularreinforcement belt surrounds a carcass intermediate the carcass and thetread in substantially symmetrical relationship to an equatorial planeof the tire. The reinforcement belt, in cross section, comprises twocrosswise spaced, opposite, laterally disposed plies of non-metallicmaterial, each folded to form a pair of confronting flap portions havingends directed toward the equatorial plane of the tire. Homologous endsof the flap portions are aligned and have respective predeterminedcrosswise spacings therebetween.

A first ply of metallic material is disposed intermediate a first pairof opposite, laterally disposed flaps in alignment with the ends of theflaps, enabling the flaps to form terminal extensions of the first plyof metallic material.

A second ply of metallic material, which can be of lesser or greatercrosswise extent than the first ply of metallic material, is arrangedadjacent the first ply of metallic material to provide at least two andat the most three layers of ply material at various points along thecrosswise width of the reinforcing belt. The crosswise extent of thesecond ply of metallic material is predetermined so as not to extendpast the marginal ends of the opposite, laterally disposed plies ofnonmetallic material. Under this arrangement the reinforcing beltconstituents include two plies of metallic material in the medianportion and two plies of nonmetallic material at the marginal endportions.

In at least one embodiment of the invention the second ply of metallicmaterial is disposed intermediate the second pair of opposite, laterallydisposed flaps in alignment with the ends of the flaps to form terminalextensions of the second ply of metallic material.

In still other embodiments of the invention only one ply of metallicmaterial is aligned with the ends of one pair of opposite, laterallydisposed flaps of nonmetallic material. The second pair of opposite,laterally disposed flaps of non-metallic material are bent over theterminal ends of the second ply of metallic material to form a thirdlayer in the median portion of the reinforcement belt.

The invention also contemplates embodiments wherein the second ply ofmetallic material is entirely disassociated from the second pair ofopposite, laterally disposed flaps of nonmetallic material, the secondply being radially inward or outward of the second pair of flaps to forma third layer in the median portion of the reinforcing belt.

In still another embodiment of the invention one ply of metallicmaterial is substantially aligned with the homologous ends of the firstand second pairs of opposite laterally disposed flaps of nonmetallicmaterial. The second ply of metallic material is arranged radiallyoutward of the first ply of metallic material and the folded flaps toform a third layer of the reinforcing belt.

The invention accordingly comprises the constructions hereinafterdescribed, the scope of the invention being indicated in the followingclaims.

In the accompanying drawing in which .[.one embodiment.]. .Iadd.severalembodiments .Iaddend.of the invention .[.is.]. .Iadd.are.Iaddend.illustrated:

FIG. 1 is a fragmentary sectional view of a pneumatic tire incorporatingone embodiment of the present invention; and,

FIGS. 2-10 are schematic representations of reinforcement beltconstructions incorporating further embodiments of the presentinvention, the belt construction being disassociated from the tireenvironment for purposes of clarity.

Referring now to the drawings, particularly FIG. 1, the pneumatic tireincludes an annular carcass 1 of known radial construction surrounded atits outerlying crown portion by a tread 2 having a crosswise width L. Areinforcement belt 3 having a crosswise width A is disposed between thetread 2 and the carcass 1 substantially symmetrical to an equatorialplane 4 of the tire.

The reinforcement belt 3 includes a median portion formed of tworadially superposed plies 5, 6 of substantially equivalent crosswiseextent, indicated by B, and incorporate metallic wires or cables such assteel. Preferably the width B of the plies 5 and 6 is 50% to 90% of thewidth L of the tread 2.

The reinforcement belt 3 also includes two opposite, laterally disposedmarginal plies 7 and 8, incorporating nonmetallic cables or filaments.Preferably the nonmetallic material is a textile form of an aromaticpolyamide base such as the synthetic material known under the trademarkdesignation Kevlar. The marginal plies 7 and 8 are folded in half toform respective flap pairs 7a, 7b and 8a, 8b. The ends of correspondingopposite, laterally disposed flaps 7a, 8a and 7b, 8b are substantiallyaligned and also substantially align with homologous terminal ends ofthe median plies 5 and 6 along substantially radial joints 9, 9'. Thusthe folded portions of the marginal plies 7, 8 are directed away fromthe equatorial plane 4, with the respective superposed ends of the flaps7a, 7b and 8a, 8b being directed toward the equatorial plane 4. Underthis arrangement the opposite, laterally disposed flaps 7a, 8a and 7b,8b form extensions of the respective .[.mediam.]. .Iadd.median.Iaddend.plies 5 and 6. The reinforcement belt is thus two layers thickat all points along its crosswise width A.

In the embodiments of FIGS. 2-9 the .[.superpose.]. .Iadd.superposed.Iaddend.median plies of metallic wires have different crosswise widthsand the superposed flaps of each folded marginal ply of nonmetallicfilaments have different crosswise widths.

In all the embodiments disclosed herein the filament, cable or wireelements in the plies of metallic and nonmetallic material have knownorientations. For example the angle of inclination of cable in the pliesof metallic material is in the range of 14° to 50°, preferably 18°. Theangle of inclination of filaments in the plies of nonmetallic materialis in the range of .[.50°.]. .Iadd.5° to 30°, preferably 12°. The plyelements are arranged at opposite angles to each other, preferablysymmetrical to the equatorial plane thereby intersecting from one layerto the other.

The reinforcement belt 3 in each of the embodiments disclosed herein, iswider than the tread 2 and extends crosswise into the shoulder areas ofthe tire. The maximum overall width A of the belt 3 is preferably 125%of the width L of the tread 2.

Referring particularly to the embodiment of FIG. 2, the reinforcementbelt comprises a relatively wide median ply 10 of metallic wire having acrosswise extent indicated by B₁ disposed radially inward of arelatively narrow median ply 11 of metallic wire having a crosswiseextent indicated by B₂. The width B₁ of the wide median ply can be of asize that is smaller than, identical to, or greater than that of thewidth L of the tread 2, whereas the width B₂ of the narrow median plycan range in size from 50% to 90% of the width L of the tread 2. Theaforesaid relationships between B₁, B₂, and the tread width L are alsoapplicable to all other hereinafter described embodiments.

The median plies 10 and 11 are arranged intermediate a pair of foldedmarginal plies 12 and 13 of nonmetallic filaments, which folded pliescomprise flaps 12a, 12b and 13a, 13b. The opposite laterally disposedflaps 12a and 13a, which are relatively narrow, align with and extendbeyond the terminal ends of the inner median ply 10 while the oppositelaterally disposed flaps 12b and 13b, which are relatively wide, alignwith and extend beyond the terminal ends of the outer median ply 11.

As shown in FIG. 2 the crosswise extents of the median plies 10 and 11are unequal and the crosswise extent of one pair of opposite, laterallyaligned flaps 12a, 13a is different from that of the other pair ofopposite laterally aligned flaps 12b, 13b. Consequently the opposite,laterally disposed flaps 12b and 13b overlap the joint between theopposite, laterally disposed flaps 12a, 13a and the terminal ends of theinner median ply 10. Also the inner median ply 10 overlaps the jointbetween the corresponding opposite laterally disposed flaps 12b, 13b andthe terminal ends of the outer median ply 11. Under this arrangement thejoints of aligned homologous ply ends at a first radial distance fromthe axis of rotation of the tire and the joints of aligned homologousply ends at a second radial distance therefrom are substantiallystaggered with respect to the equatorial plane 4, with the reinforcementbelt being two layers thick at all points along its crosswise width.

The embodiment of FIG. 3, which is substantially a mirror image of theembodiment of FIG. 2, comprises a relatively narrow median ply 14 ofmetallic wire disposed radially inward of a relatively wide median ply15 of metallic wire. The median plies 14 and 15 are arrangedintermediate a pair of folded marginal plies 16 and 17 of nonmetallicfilaments, which folded plies respectively comprise flaps 16a, 16b and17a, 17b. The opposite disposed flaps 16a, 17a, and 16b, 17b extendbeyond the terminal ends of the respective median plies 14 and 15 insubstantial alignment therewith, and the joints between alignedhomologous ply ends are symmetrically staggered with respect to theequatorial plane 4 as previously described. The reinforcement belt isthus two layers thick at all points along its crosswise width.

In the embodiment of FIG. 4 the reinforcement belt comprises therelatively wide median ply 10 disposed radially inward of the relativelynarrow median ply 11. A pair of folded marginal plies 12' and 13',arranged at opposite ends of the median plies 10 and 11, compriseopposite, laterally disposed relatively narrow flaps 12'a and 13'ahaving ends that form an aligned joint with the terminal ends of theinner median ply 10. The flaps 12'a and 13'a thus form an extension ofthe inner median ply 10.

The folded marginal plies 12' and 13' also include relatively wide flaps12'b-12'c and .[.13'b-13°c.]. .Iadd.13'b-13'c .Iaddend.bent over therespective terminal ends of the outer median ply 11. The respectivebends or steps are defined between the flap portions 12'b, 12'c and13'b, 13'c. The corresponding opposite, laterally disposed flap portions12'b and 13'b are substantially coplanar with the outer median ply 11thereby forming an extension of the ply 11. The corresponding opposite,laterally disposed flap portions 12'c and 13'c overlay the terminal endsof the ply 11 by an amount m. The dimension m preferably ranges from 10%of the tread width L to 50% of the width of the narrow median ply. Thusthe reinforcement belt is two layers thick at its marginal end portions,three layers thick at laterally spaced sections defined between theterminal ends of the median play 11 and the free ends of the flapportions 12'c and 13'c, and two layers thick in the region intermediatethe laterally spaced three layer sections.

In the embodiment of FIG. 7, which is substantially a mirror image ofthe FIG. 4 embodiment, the reinforcement belt comprises the relativelynarrow median ply 14 disposed radially inward of the relatively widemedian .[.play.]. .Iadd.ply .Iaddend.15. A pair of folded marginal plies16' and 17', arranged at opposite ends of the median plies 14 and 15,includes opposite, laterally disposed, relatively narrows flaps 16'b and17'b having ends that form an aligned joint with the terminal ends ofthe outer median ply 15.

Each of the folded plies 16', 17' also include relatively wide flaps16'a-16'c and 17'a-17c bent over the respective terminal ends of theinner median ply 14. The respective bends or steps are defined betweenthe flap portions 16'a, 16'c and 17'a, 17'c. The corresponding opposite,laterally disposed flap portions 16'a and 17'a are substantiallycoplanar with the inner median ply 14, thereby forming an extension ofthe ply 14. The corresponding opposite laterally disposed flap portions16'c and 17'c overlay the terminal ends of the median ply 14 by equalamounts m previously described with respect to the embodiment of FIG. 4.Thus the reinforcement belt is two layers thick at its marginal endportions, three layers thick at laterally spaced sections definedbetween the terminal ends of the median ply 14 and the free ends of theflap portions 16'c and 17'c, and two layers thick in the regionintermediate the laterally spaced three layer sections.

The reinforcement belt of the embodiment of FIG. 5 includes therelatively narrow median ply 14 disposed radially inward of therelatively wide median ply 15. A pair of folded marginal plies 16', 17'are disposed at opposite ends of the median plies 14, 15 in anarrangement resembling that of the embodiment of FIG. 7. The oppositelaterally disposed flaps 16'b and 17'b, which are relatively narrow,form an aligned joint with the terminal ends of the outer median ply 15in a manner identical to that of the FIG. 7 embodiment. The flaps 16'band 17'b thus form terminal extensions of the ply 15.

The opposite, laterally disposed flaps 16'a-16"c and 17'a-17"c, whichare relatively wide, are bent over the terminal ends of the inner medianply 14, the respective bends being defined between the flap portions16'a, 16"c and 17'a, 17"c. The crosswise extent of each flap 16'a, 16"cand 17'a, 17"c is indicated by A/2 which represents approximately onehalf of the overall belt width A measured between the folded ends of themarginal plies 16' and 17'.

As in the FIG. .[.5.]. .Iadd.6 .Iaddend.embodiment the substantiallyaligned opposite laterally disposed flap portions 16'a and 17'a aresubstantially coplanar, with the inner median ply 14 thereby forming anextension of the ply 14. The substantially aligned opposite, laterallydisposed flap portions 16"c and 17"c overlay substantially the entirecrosswise extent of the inner median ply 14. Thus the embodiment of FIG.5 differs from the embodiment of FIG. 7 by the provision of theelongated flap portions 16"c and 17"c. Under this arrangement thereinforcement belt is two layers thick at its marginal end portions andthree layers thick along the median portion between the terminal ends ofthe narrow median ply 14.

In the embodiment of FIG. 6 the reinforcement belt comprises therelatively wide median ply 10 disposed radially inward of the relativelynarrow median ply 11. A pair of folded marginal plies 18 and 19 arearranged at the terminal ends of the .[.mediam.]. .Iadd.median.Iaddend.ply 11 and include opposite, laterally disposed relativelynarrow flaps 18a and 19a having ends that form an aligned joint with theterminal ends of the narrow median ply 11. The flaps 18a and 19a thusform an extension of the ply 11.

The folded plies 18 and 19 also include opposite, laterally.[.dispose.]. .Iadd.disposed.Iaddend., relatively wide flaps 18b and 19bpositioned radially beyond the relatively narrow median ply 11 so as tostraddle the radially outer side of the joints between the opposite,laterally disposed flaps 18a, 18a and the terminal ends of the ply 11 tooverlap the ply 11 by equal amounts m previously described with respectto the embodiment of FIG. 4. The relatively wide median ply 10 straddlesthe radially inner side of said joints without extending to the marginalends of the folded plies 18 and 19. Under this arrangement thereinforcement belt is two layers thick at its marginal end portions,three layers thick at laterally spaced sections defined between theterminal ends of the median ply 10 and the free ends of the flaps 18b,19b, and two layers thick in the region intermediate the laterallyspaced three layer sections.

In the embodiment of FIG. 8, which is substantially a mirror image ofthe embodiment of FIG. 6, the reinforcement belt comprises therelatively narrow median ply 14 disposed radially inward of therelatively wide median ply 15. A pair of folded marginal plies 18' and19' are arranged at the terminal ends of the median ply 14 and includeopposite, laterally disposed, relatively wide flaps 18'b and 19'b havingends that form aligned joints with the respective terminal ends of thenarrow median ply 14. The flaps 18'b and 19'b thus form an extension ofthe ply 14.

The folded plies 18' and 19' also include opposite, laterally disposedrelatively wide flaps 18'a and 19'a positioned radially inward of therelatively narrow median ply 14 so as to straddle the radially innerside of the joints between the opposite, laterally disposed flaps 18'b,19'b and the terminal ends of the ply 14 to overlay the end portions ofthe ply 14. The relatively wide median ply 15 straddles the radiallyouter side of said joints without extending to the marginal ends of thefolded plies 18' and 19'. Under this arrangement the reinforcement beltis two layers thick at its marginal end portions, three layers thick atlaterally spaced sections defined between the terminal ends of themedian ply 15 and the free ends of the flaps 18'a, 19'a, and two layersthick in the region intermediate the laterally spaced three layersections.

A pneumatic tire incorporating the FIG. 8 embodiment has beenmanufactured in accordance with the following characteristics.

    ______________________________________                                        Item                   Dimension                                              ______________________________________                                        Tire size              185 R × 14                                       Tread width            L = 120 mm.                                            Overall belt width     A = 150 mm.                                            Width of the wide ply (15)                                                    of metallic material   B.sub.1 = 130 mm.                                      Width of the narrow ply (14) of                                               metallic material      B.sub.2 = 90 mm.                                       Width of the narrow flaps (18'b,                                              19'b) of nonmetallic material                                                                        30 mm.                                                 Width of the wide flaps (18'a,19'a)                                           of nonmetallic material                                                                              40 mm.                                                 Overlap of the narrow ply of                                                  metallic material (14) on each wide                                           flap (18'a,19'a) of monmetallic                                               material               m = 10 mm.                                             Angle of inclination of the cables of                                         metallic and nonmetallic material                                                                    ± 18°                                        ______________________________________                                    

In the embodiment of FIG. 9 the reinforcement belt comprises therelatively narrow median ply .[.15.]. .Iadd.14 .Iaddend.disposedradially inward of the relatively wide median ply 15. A pair of foldedmarginal plies 18' and 19' are arranged at the terminal ends of themedian ply 14 and include opposite, laterally disposed, relativelynarrow flaps 18'b and 19'b having ends that form an aligned joint withthe terminal ends of the narrow median ply 14. The flaps 18'b and 19'bthus form an extension of the median ply 14.

The folded plies 18' and 19' also include opposite, laterally disposed,relatively wide flaps 18'a and 19'a positioned radially inward of therelatively narrow median ply 14. The ends of the flaps 18'a and 19'aextend to the equatorial plane 4 thereby straddling the radially innerside of the joints between the opposite laterally disposed flaps 18'b,19'b and the terminal ends of the ply 14. The relatively wide median ply15 straddles the radially outer side of said joints without extending tothe marginal ends of the folded plies 18' and .[.10'..]. .Iadd.19'..Iaddend.Under this arrangement the reinforcement belt is two pliesthick at the marginal end portions and three plies thick at the medianportion defined between the terminal ends of the median ply 15.

In the embodiment of FIG. 10 the reinforcement belt comprises therelatively narrow median ply 14 disposed radially inward of therelatively wide median ply 15. A pair of laterally spaced marginal plies20 and 21 are respectively folded in half to form the flap pairs 20a,20b and 21a, 21b. The .[.opposiite.]. .Iadd.opposite.Iaddend., laterallydisposed flaps 20a, 21a and 20b, 20b are substantially aligned and alsosubstantially align with terminal ends of the median ply 14. Thesuperposed flaps 20a, 20b and 21a, 21b thus substantially formextensions of the median ply 14.

The relatively wide median ply 15 straddles the radially outer side ofthe joints between the terminal ends of the ply 14 and the opposite,laterally disposed flaps 20a, 21a and 20b, 21b. Under this arrangementthe reinforcement belt is two layers thick at its marginal end portions,three layers thick at laterally spaced sections defined between theterminal ends of the median ply 15 and the ends of the flaps 20a, 20band 21b, and two layers thick in the region intermediate the three layersections.

As will be apparent to those skilled in the art the median plies ofmetallic material do not extend between confronting folded portions ofthe marginal plies of nonmetallic material.

Some advantages of the present invention evident from the foregoingdescription .[.includea.]. .Iadd.include a .Iaddend.tire having a.[.reinforcementbelt.]. .Iadd.reinforcement belt .Iaddend.withrelatively lightweight, substantially inextensible marginal edgeportions for reducing the undesirable gyroscopic effect and therebyfacilitating operation of the steering wheel. The use of Kevlar materialor an equivalent substance in the marginal plies renders said plieslightweight and substantially inextensible. The disclosed arrangementsof marginal nonmetallic filament plies with median plies of metallicmaterial improves travel .[.confort.]. .Iadd.comfort .Iaddend.andminimizes the hazard of belt ply separation at the edges of the tread,since the plies of metallic materal are intermediate the edge portionsof the belt.[.,.]. .Iadd.and .Iaddend.are not turned up. A furtheradvantage is that there are not less than two plies nor more than threeplies of belt material at all points throughout the crosswise extent ofthe reinforcing belt and no ply surrounds another ply. Moreover theplies of nonmetallic material are not inserted between plies of metallicmaterial, and the plies of metallic material are not inserted betweenconfronting folded portions of the plies of nonmetallic material, makingit possible to reduce the number of superposed plies or flaps to aminimum. The disclosed tire construction .[.incorpoarates.]..Iadd.incorporates .Iaddend.a reinforcement belt .[.or.]. .Iadd.of.Iaddend.relatively simple design, is economical to maufacture since atwo part vulcanization mold can be used, and provides improved operatingreliability.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. A pneumatic tire comprising an annular carcasshaving a radially outerlying crown portion, a tread constituting anannular cover surrounding the crown portion of said carcass, and anannular reinforcement belt interpositioned between the crown portion ofsaid carcass and said tread, said reinforcement belt comprising, incross-section, a pair of opposite, laterally disposed, crosswise spaced,first and second plies of a first cord material, each of said first andsecond plies being folded to form two respective flap portions havingends directed toward an equatorial plane of the tire and respectivefolded margins directed away from said equatorial plane, one of theflaps of each said first and second folded ply confronting at least aportion of the other said respective flap, a first ply of second cordmaterial having opposite terminal ends being disposed between homologousends of one of the pairs of corresponding opposite, laterally disposedflap portions such that said one pair of opposite, laterally disposedflap portions extends laterally beyond corresponding terminal ends ofsaid first ply of second cord material in substantial alignment withsaid corresponding opposite terminal ends, and a second ply of saidsecond cord material having opposite terminal ends, said second ply ofsecond cord material being disposed adjacent said first ply of secondcord material such that said second ply of second cord material does notextend laterally beyond the folded margins or between the confrontingflap portions of the first and second folded plies, whereby said firstand second plies of the first cord material are positioned at themarginal ends of said reinforcement belt and said first and second pliesof the second cord material are positioned at the median portion of thereinforcement belt.
 2. A pneumatic tire as claimed in claim 1 whereinsaid first cord material comprises textile cords and said second cordmaterial comprises metallic wire cords.
 3. A pneumatic tire as claimedin claim 2 wherein said textile cord material is formed of a syntheticsubstance on an aromatic polyamide base identified by the trade nameKevlar.
 4. A pneumatic tire as claimed in claim 1 wherein saidreinforcement belt is symmetrical with respect to the equatorial planeof said tire.
 5. A pneumatic tire as claimed in claim 1 whereinhomologous ends of the first and second pairs of corresponding opposite,laterally disposed flaps are crosswise aligned.
 6. A pneumatic tire asclaimed in claim 1 wherein said first pair of corresponding opposite,laterally disposed flap portions constitute substantially contiguous.[.extension.]. .Iadd.extensions .Iaddend.of said first ply of secondcord material.
 7. A pneumatic tire as claimed in claim 1 wherein thecrosswise width of said reinforcement belt has a maximum width of 125%of the tread width.
 8. A pneumatic tire as claimed in claim 7 whereinthe second ply of second cord material is of a different crosswiseextent than the first ply of second cord material, the narrower of saidplies of second cord material ranging in size from 50% to 90% of thecrosswise width of said tread.
 9. A pneumatic tire as claimed in claim 8wherein the wider of said plies of second cord material ranges in sizefrom a crosswise extent less than said tread width to a crosswise extentgreater than said tread width.
 10. A pneumatic tire as claimed in claim1 wherein said second ply of second cord material is of lesser crosswiseextent than the crosswise distance from one of the folded margins to theother said folded margin.
 11. A pneumatic tire as claimed in claim 1wherein said second ply of second cord material is disposed betweenhomologous ends of the other pair of corresponding opposite, laterallydisposed flap portions such that said other pair of correspondingopposite, laterally disposed flap portions extend crosswise beyondcorresponding terminal ends of said second ply of second cord materialin substantial alignment with the corresponding terminal ends of saidsecond ply of second cord material.
 12. A pneumatic tire as claimed inclaim 11 wherein said other pair of corresponding opposite, laterallydisposed flap portions constitute substantially contiguous extensions ofsaid second ply of second cord material.
 13. A pneumatic tire as claimedin claim 11 wherein the crosswise extent of the first and second pliesof second cord material are substantially equivalent.
 14. A pneumatictire as claimed in claim 13 wherein the crosswise extent of said firstand second plies of second cord material is within the range of 50% to90% of the crosswise width of said tread.
 15. A pneumatic tire asclaimed in claim 11 wherein said .[.frist.]. .Iadd.first .Iaddend.ply ofsecond cord material is of greater crosswise extent than the second plyof second cord material.
 16. A pneumatic tire as claimed in claim 1wherein the crosswise extent of each flap portion is substantiallyequivalent.
 17. A pneumatic tire as claimed in claim 1 wherein thecrosswise extent of each flap of the other pair of correspondingopposite, laterally disposed flap portions is greater than the crosswiseextent of each flap of said one pair of corresponding opposite,laterally disposed flap portions.
 18. A pneumatic tire as claimed inclaim 17 wherein said second ply of second cord material is disposedbetween homologous free ends of the other pair of correspondingopposite, laterally disposed flap portions such that said other pair ofcorresponding opposite, laterally disposed flap portions extendcrosswise beyond the corresponding terminal ends of said second ply ofsecond cord material in substantial alignment with the correspondingterminal ends of said second ply of second cord material.
 19. Apneumatic tire as claimed in claim 18 wherein the first ply of secondcord material is of greater crosswise extent than the second ply ofsecond cord material and is disposed radially inward of the second plyof second cord material.
 20. A pneumatic tire as claimed in claim 18wherein the first ply of second cord material is of lesser crosswiseextent than the second ply of second cord material and is disposedradially inward of the second ply of second cord material.
 21. Apneumatic tire as claimed in claim 17 wherein said one pair ofcorresponding opposite, laterally disposed flap portions is disposedradially outwardly of said other pair of corresponding opposite,laterally disposed flap portions.
 22. A pneumatic tire as claimed inclaim 21 wherein the second ply of second cord material is of greatercrosswise extent than the first ply of second cord material and isdisposed radially outward of the first ply of second cord material. 23.A pneumatic tire as claimed in claim 20 wherein the crosswise extent ofeach flap of the other pair of corresponding opposite, laterallydisposed flap portions is approximately one-half the crosswise distancebetween said folded margins.
 24. A pneumatic tire as claimed in claim 17wherein each flap of said one pair of corresponding opposite, laterallydisposed flap portions is disposed radially inward of said other pair ofcorresponding opposite, laterally disposed flap portions.
 25. Apneumatic tire as claimed in claim 24 wherein the second ply of secondcord material is of greater crosswise extent than the first ply ofsecond cord material and is disposed radially inward of the first ply ofsecond cord material.
 26. A pneumatic tire as claimed in claim 17wherein each flap of the other pair of corresponding opposite, laterallydisposed flap portions overlaps the terminal ends of one of the plies ofsecond cord material.
 27. A pneumatic tire as claimed in claim 26wherein the crosswise width of said overlap is at least 10% of the treadwidth.
 28. A pneumatic tire as claimed in claim 17 wherein said secondply of second cord material is of greater crosswise extent than thecrosswise space between homologous free ends of said other pair ofcorresponding opposite, laterally disposed flap portions, said otherpair of corresponding opposite, laterally disposed flap portions beingfolded over the terminal ends of said second ply of second cord materialand being substantially coplanar with said second ply of second cordmaterial between the folded over portion and the folded margins.
 29. Apneumatic tire as claimed in claim 28 wherein said second ply of secondcord material is of lesser crosswise extent than said first ply ofsecond cord material.
 30. A pneumatic tire as claimed in claim 29wherein said second ply of second cord material is disposed radiallyoutward of said first ply of second cord material.
 31. A pneumatic tireas claimed in claim 29 wherein said second ply of second cord materialis disposed radially inward of said first ply of second cord material.32. A pneumatic tire as claimed in claim 31 wherein the crosswise extentof each flap of said other pair of corresponding opposite, laterallydisposed flap portions is approximately one-half the crosswise distancebetween said folded marginal ends.
 33. The pneumatic tire as claimed inclaim 32 wherein the ends of said other pair of opposite, laterallydisposed flap portions form a butt joint substantially at saidequatorial plane.
 34. A pneumatic tire as claimed in claim 16 whereinsaid other pair of corresponding opposite, laterally disposed flapportions extend crosswise beyond the corresponding terminal ends of saidfirst ply of second cord material in substantial alignment with saidcorresponding opposite terminal ends, said second ply of second cordmaterial being disposed radially outward of said first and second foldedplies and said first ply of second cord material.